Printing mechanism for calculating machine

ABSTRACT

A calculating machine having a mechanism for placing the accumulator rack in a neutral position during non-add and correction operations, a correction key and print prevention mechanism operated by the correction key to prevent the printing of erroneous values that have been registered by the depression of digit keys by the operator, a ratcheting mechanism for winding the ribbon onto a first spool from a second spool including mechanism for reversing the winding and a reciprocal drive bar and a mechanism for shifting from one band of a first color to another band of a second color of a two-band ribbon so that the second band is utilized in the printing operation during certain predetermined machine operations such as the total and non-add operations.

United States Patent Kawamura et a1.

[54] PRINTING MECHANISM FOR CALCULATING MACHINE [72] Inventors: Toshiki Kawamura, Narashino-shi; Tohru Ohneda, Funabashi-shi, both of Japan [73] Assignee: Kabmhiki Kaisha Hattori Tokeiten [22] Filed: Dec. 30, 1968 [21] Appl. No.: 787,927

52 us. C1. ..235/5s P, 235/6019, 235/6025, 235/60.26, 235/6051, 197/151 51 Int. Cl. ..G06c 29/00 [58] Field of Search ..235/58 R, 58 P, 60 R, 60 P, 235/6025, 60.26, 60.19, 60.51, 60.52;

[151 3,682,376 51 Aug. 8, 1972 Okuda ..235/58 P ABSTRACT A calculating machine having a mechanism for placing the accumulator rack in a neutral position during nonadd and correction operations, a correction key and print prevention mechanism operated by the correction key to prevent the printing of erroneous values that have been registered by the depression of digit keys by the operator, a ratcheting mechanism for winding the ribbon onto a first spool from a second spool including mechanism for reversing the winding and a reciprocal drive bar and a mechanism for shifting from one band of a first color to another band of a second color of a two-band ribbon so that the second band is utilized in the printing operation during certain predetermined machine operations such as the total and non-add operations.

15 Claims, 8 Drawing Figures PKTENTED 8 3.682.376

SHEET 3 [IF 5 The present invention relates to a calculating machine that prints numerical values and symbols in response to the depression by an operator of various keys on the machine which in turn produce movement of a platen into engagement with a plurality of type discs upon each of which are mounted a plurality of raised numbers and other symbols.

Conventional calculating machines are equipped with mechanisms for preventing the printing of erroneous values on recording paper after the operator has discovered that the digit keys that he has depressed are incorrect. In each prior art mechanism, when a correction key is depressed a stopper element is inserted into a yielding accumulator rack that is part of the calculating mechanism of the machine, to stop the calculating operation of the rack. Such print prevention mechanism has certain disadvantages for example, although the motion of the yielding accumulator rack is interrupted the platen is moved and pressed against blank typeless sections of the type discs thereby preventing the recordation of numerical values or symbols, however the recording paper is stained by its contact with the ribbon when the platen is moved against the blank sections. Another disadvantage of such prior art mechanisms is that not only a stopper element and associated parts are necessary but in addition, there is required mechanism for holding the feed of the recording paper at the same time that the stopper element is actuated thereby making the machine more complicated and therefore more expensive and, in addition, increasing the size thereof.

The prior art calculating machines utilize ribbon drive mechanism that includes a drive lever for driving either one of a pair of pawls into meshing engagement with a ribbon driving ratchet arranged on the left or right side of the machine for causing a rocking movement to shift the ratchet in either direction left or right. Such driving mechanism requires a relatively large space inside of the calculating machine to accommodate the rocking movement of the ribbon drive lever which is particularly disadvantageous for calculating machine manufacturers who are currently striving to reduce the size of such machines.

The present invention provides in a calculating machine of the type described print prevention mechanism that includes a platen mounted opposite to the type-discs and drive means for bringing the platen into or out of printing contact with the type-discs and a further mechanism for preventing the drive means from moving the platen into printing contact with the typediscs when a correction key is depressed, thereby preventing the staining of the recording paper during the correction operation. In addition, the present invention provides a ribbon driving mechanism including a pair of ratchet drive mechanisms each provided with a spool, and a drive bar means that extends from one of the ratchet drive mechanisms to the other including an endwise reciprocal drive bar that actuates either one of the ratchet mechanisms and means for reciprocating the drive bar. The arrangement thus provided including the endwise reciprocal drive bar requires less space then the comparable mechanism for the prior art calculating machine as described above. Furthermore, the

present invention provides a ribbon shifting mechanism for a two-color band ribbon that prevents the utilization of one of the bands except during certain predetermined machine operations such as the total and nonadd operations.

It is, therefore, an object of the present invention to I provide an improved calculating machine.

It is another object of the present invention to provide mechanism for a calculating machine that places the machine accumulator rack in a neutral position during the non-add and correction operations.

It is still another object of the present invention to provide apparatus in a calculating machine that prevents the staining of the recording paper during a correction operation caused by the registering of incorrect numerals and symbols.

It is a further object of the present invention to provide, in a calculating machine, improved mechanism for winding the ribbon onto one spool from another and for the winding operation.

It is a still further object of the present invention to provide improved mechanism for shifting a multiband ribbon from one to the other of the bands.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the function, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

FIG. 1 is an elevational side view partially in section and broken away of the printing drive mechanism of the present invention;

FIG. 2 is an elevational side view of the platen drive arm shown in FIG. 1;

FIG. 3 is an elevational side view partially in section and broken away of a portion of the present invention that includes mechanism for setting an accumulator to the neutral position;

FIG. 4 is an elevational side view partially in section and broken away of a portion of the present invention;

FIG. 5 is an elevational side view, broken away, of a ribbon drive mechanism and a band shifting mechanism for the present invention;

FIG. 6 is a plan view, on a reduced scale, of the ribbon drive mechanism shown in FIG. 5;

FIG. 7 is a plan view of a portion of the mechanism shown in FIG. 6 with some of the elements in a different position; and

FIG. 8 is an elevational side view partially in section and broken away of a releasing mechanism for a spool holder for a band shifting mechanism according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the present invention a print-stop apparatus includes three mechanisms connected to a correction key, i.e., release mechanism for a platen drive arm, mechanism for moving an accumulator to its neutral position and mechanism for holding the release mechanism and neutral position mechanism in their operative positions when the correction key is actuated.

A drive mechanism for a platen will now be described. Referring moreparticularly to FIG. 1, a cam shaft 1 driven by a motor (not shown) has mounted thereon a cam 3 from which extends a drive roller pin 2. An elongated somewhat irregularly shaped platen drive lever 4 is mounted for rocking movement on a shaft 5 intermediate to the ends of the lever 4, and has connected to one end section a drive pin 6 which extends transversely of the lever 4, the other end section of the lever 4 being formed as a cam follower 9. A biasing spring 8 is connected to one end of the platen drive lever 4 constantly biasing same in the clockwise direction as viewed in FIG. 1. Near the cam follower end section of the lever 4 between the shaft 5 and the cam follower section 9 there is formed an aperture 10 which receives a pin 1 1, that is fixedly secured at either end to a pair of parallel side plates 34. Mounted by one end for rocking movement on the pin 6 is a platen drive arm 7. The arm 7, shown more clearly in FIG. 2, is elongated and is formed at the end opposite to which the spring 8 is connected with an edge that is indented to form a shoulder 14 adjacent a slot or indent 15 that opens out of the edge of the lever. To the bottom (FIG. 2) edge of the platen drive arm 7 there is secured by one end a coil spring 7a which is secured by its other end to a pin connected to the platen drive lever 4 between the shaft 5 and the drive pin 6, the spring 7a tending to bias the platen drive arm 7 in a counterclockwise direction as seen in FIG. 2.

The bias exerted by the coil spring 7a on the platen drive arm 7 serves to keep the shoulder 14 of the drive arm 7 in engagement with a pin 13 connected to an intermediate section and extending transversely of a platen arm 12 mounted by one end section on two pins 16 each of which is supported by the side plates 34. The platen arm 12 is bifurcated at the end section opposite to the pin mounted section, each arm of the bifurcated end section being connected by pins 17 to a platen holder 18. The platen holder 18 supports a platen shaft 19 which in turn carries a platen 20 and each end sec- I tion of the platen shaft 19 supports a ratchet wheel 21 utilized to rotate the platen. Mounted on the platen holder 18 is a click shaft 22 on which is mounted for rocking motion a click lever 23 at the free end of which is rotatably supported a click roller 24 engageable with the ratchet wheels 21. The platen 20 is biased to the right as seen in FIG. 1 by a coil spring 25 which is connected by one end to the click shaft 22 and by its other end to a fixed pin. A feed pawl 26 for the ratchet wheels 21 is mounted for rocking movement by one end section to a shaft 27, that end section including a raised portion to which is secured a pin to which is connected one end of a spring 28, the other end of which is connected to a fixed pin, the pin 28 serving to bias the feed pawl 26 in a clockwise (FIG. 1) direction to bring the other end section of the feed pawl into meshing engagement with the ratchet wheel 21. A type disc 29 on the outer peripheral surface of which is mounted the type that is utilized by the calculating machine is driven in rotation by a rack 32 through the intermediacy of the connecting wheels and 31.

As the cam 3 is driven by the motor (not shown) in a clockwise direction as shown in FIG. 1 by the appropriate arrow, the drive roller pin 2 follows around in the clockwise direction into camming engagement with the cam follower 9 which thereupon pivots the platen drive lever 4 about the pin 5 in a counterclockwise direction, the length of the aperture 10 being sufficient to allow movement of the lever 4 relatively to the pin 11. As the lever 4 pivots in a counterclockwise direction, the platen drive arm 7 is moved to the left (FIG. 1) thereby to drive the pin 13 to the left and pivot the platen arm 12 and the platen and platen holder into contact with the type-disc 29 effecting the printing desired. As the platen 20 pivots towards the type-disc 29, the feed pawl 26 slips back over one of the teeth of the ratchet wheel 21. Thus, when the platen 20 is returned to its original position after printing by the coiled return spring 25, the ratchet wheel 21 is rotated clockwise (FIG. 1) the distance of one of the teeth of the ratchet wheel, or to put it another way, by one click, thereby to feed the recording paper (not shown) forward by that amount. It is noted that the recording paper (not shown) is mounted in the usual manner, therefore, a further description of the same is not necessary.

The platen drive release mechanism which is utilized to operate the platen will now be described. Referring to FIG. 1, there is shown a correction key 35 whose supporting shaft extends upwardly to a keyboard 33. The correction key 35 and its supporting shaft is movable endwise as a guide pin 37 supported by the side plates of the machine are received by a guide slot 36. A mechanical linkage system is provided for pivoting the link 44 and includes a correction link 38 is mounted for rocking movement about a shaft 39, the link 38 being formed with an extension 38a adapted to be driven downwardly (FIG. 1) by the correction key 35. As the correction link 38 is rocked, the transit lever 41 is also rocked through the intermediacy of a connection link 40, thereby to rock the rod 42 upon which one end of the lever 41 is connected. As the correction link 38 is rocked, the connecting rod 43 is moved endwise, thereby to rock the link 44which rotates a release shaft 45 to which the link 44 is connected. Secured to the release shaft 45 is a clutch or release pin 46 which, when the shaft 45 is rotated in a counterclockwise direction (FIG. 1), is brought into engatement with the lower edge of the platen drive arm 7 which is thereupon moved upwardly.

A description of the operation of the platen drive release mechanism described immediately above will now be set forth. As the correction key 35 is depressed by the operator, the extension 38a is moved downwardly in the same direction as the key 35 thereby rocking the correction link 38 in a counterclockwise (FIG. 1) direction as indicated by the appropriate arrow in FIG. 1. As a result, the rod 42 is rotated counterclockwise and, simultaneously, the release shaft 45 is also rotated in a counterclockwise direction which brings the clutch or release pin 46 into engagement with the platen drive arm 7 to move the arm 7 upwardly against bias of the spring 7a. As a result, the drive pin 13 is moved off of the shoulder 14 and into alignment with the slot 15. Thus, when the cam 3 is rotated thereby rocking the platen drive lever 4 and the platen drive arm 7 the platen 20 is not moved into engagement with the type-disc 29 because the platen drive arm 7 merely reciprocates relatively to the pin 13 which moves in and out of the slot 15. Since the pin 13 is not pushed by the drive arm 7, the platen arm 12 is not pivoted and therefore, the platen itself is not moved towards the type-disc 29, thereby preventing any printing on the recording paper, and, in addition, preventing the feeding of the recording paper because the ratchet wheels are not rotated.

At this point the mechanism for moving an accumulator into its neutral position will be described. The calculating machine of the present invention includes a calculating mechanism (not all of which is shown) which includes an accumulator having a number of pairs of accumulator gears for performing the addition and subtracting functions of the machine. Each of the accumulator gears has ten teeth which function as a memory device and a yielding accumulator rack which is driven in accordance with a value-entry operation to rotate the accumulator gears for addition and subtraction thereby to enable the gears to memorize the values. In calculating machines equipped with such a calculating mechanism, it is essential that the accumulator gears for addition and subtraction be kept out of engagement with the yielding accumulator rack, or in neutral positions, during the correction and non-add operations.

Referring now more particularly to FIG. 3, a non-add key 47 and its supporting shaft, arranged for endwise movement through the keyboard 33 is connected by suitable pins to intermediate levers 48 and 49 which are mounted for rocking movement about the shaft 70 and 70a, respectively, positioned intermediate the ends of the respective levers. The intermediate lever 49 is connected by one end through a pin to a release lever 50 which is pivotally supported by a shaft 71. Release lever 50 includes a detent extension 51 which functions to retain a non-add lever 52 in an inoperative position. When the non-add key is actuated or depressed, the release lever 50 is moved out of engagement with the non-add lever 52, thereby allowing the non-add lever 52 to move to the right (FIG. 3) by the force exerted by the spring 53 which is connected by one end to the lever 52 and by the other end to a fixed pin, thereby controlling the usual cam mechanism that controls the gearing timing for the gears and the rack of the accumulator, thereby maintaining the accumulator in a neutral position. According to the present invention, the correction gear 35 is interlocked with the release lever 50 for the non-add key for placing the accumulator in its neutral position. To accomplish this, a neutral lever 54 secured to the rod 42 is connected by a pin to a connecting rod 56 in which is formed a slot 55 that in turn receives a pin 57 which connects the intermediate levers 48 and 49 end to end. Consequently, when the correction key 35 is depressed by the operator the rod 42 is rotated counterclockwise as described above and the neutral lever 54 which is secured to the rod 42 is also turned in a counterclockwise direction, thereby pulling the connecting rod 56 upwardly (FIG. 2). When this happens, the pin 57 is rotated counterclockwise about the shaft 57a and the release lever 50 is pivoted in a clockwise direction around the shaft 71 thereby releasing the non-add lever 52. Thus, the non-add lever 52 is moved to the right (FIG. 2) when either the nonadd key 47 or the control key 35 is depressed to place the accumulator in its neutral position. Thereupon, any further depression of the non-add key, i.e., when the correction key 35 has been depressed, is nullified by the slot 55 and the motion initiated by the depression of the non-add key is not transmitted to the correction key.

A further mechanism will now be described which is designed to maintain the platen drive arm 7 released and the accumulator retracted to the neutral position by the operation of the release mechanism and the mechanism for moving an accumulator to its neutral position, respectively, as described above as the cam shaft 1 makes one complete revolution. Thus, referring in particular to FIG. 4, a correction detent lever 58 is secured to the rod 42 and biased in a clockwise direction by a spring 59 connected by one end to the free end of the lever 58 and by its other end to a fixed pin. The other end of the lever 58, which is secured intermediate its ends on the rod 42, is formed with a pawl 60 which engages a hook 62 of a detent lever 61. The detent lever 61 is formed with an engaging hook 62 adjacent to which is formed a detent 63, the detent lever 61 being mounted for rocking movement on a shaft 64 at one end section of the lever 61, the other end section of the lever 61 being provided with a stop pin 65. A spring 66 is connected by one end to the pin and by its other end to a fixed pin, thereby biasing the lever 61 in a counterclockwise direction and to the right as seen in FIG. 4. Reset transit lever 68, 69 and a reset lever 67 are provided for interlocking connection with the motor driven cam mechanism.

With the apparatus as described above, when the correction key 35 is depressed and the rod 42 is rotated counterclockwise, the correction detent lever 58 is also turned counterclockwise (FIG. 4) against the bias of the spring 59 to disengage the pawl 60 from the engageable hook 62. Consequently, the detent lever 61 is moved to the right to the position shown by the dotted lines in FIG. 4, by the force exerted by the spring 66, thereby to bring the pawl 60 into engagement with the detent 63 and the stop pin 65 into engagement with the reset transit lever 68. In this position of the correction detent lever 58, the rod 42 cannot return to its original position and the release mechanism and the mechanism for moving an accumulator to its neutral position, as described above, are retained in the positions resulting from a depression of the correction key 35.

Since the reset transit levers 68, 69 and 67 are operatively connected to the motor-driven cam mechanism, when the cam shaft has rotated through a predeten mined angle the reset transit levers 68, 69 and 67 are moved to the left (FIG. 4) thereby to move the stop pin 65 to the left so that the detent lever 61 is also moved to the left against the bias of the spring 66, thereby moving the detent 63 out of engagement with the pawl 60. Then the detent lever 58 is turned clockwise (FIG. 4) by the force exerted by the spring 59 into engagement once again with the engaging hook 62, thereby allowing the rod 42 to return to its original position and complete the correction operation. As described, the depression of the correction key is transmitted to the non-add mechanism for an interlocking operation. Thus, the accumulator can be retained in a neutral position without the necessity of utilizing any additional attachments and without the need for changing the values being retained by the memory function of the accumulator. Furthermore, because the correction key can be retained in a depressed position by a simple lever mechanism cooperating therewith, the correction operation can be completed while the cam shaft makes one complete revolution.

Turning now to the drive mechanism for the ribbon winding apparatus of the printing mechanism, the drive mechanism is also actuated by the operation of the cam shaft 1. Referring now more particularly to FIGS. and 7, the cam shaft 1 has mounted thereon a cam 72 on which is mounted a roller 73 which extends transversely of the cam 72. A fork 74 formed with two parallel spaced arms 76 and 77 and a base arm 78 is mounted for rocking movement on a shaft 75 at the junction of the arms, the shaft 75 being supported by and between the parallel side plates 34. Mounted on and extending transversely of the base arm 78 is a connecting pin 79 which in turn is connected to one end of a connecting lever 80, as seen more clearly in FIG. 6. On the other end of the connecting lever 80, there is formed a substantially L-shaped slot 81 having stability points 81a and 81b at each end thereof. A bell crank lever 82 is mounted for rocking movement on a shaft 84 at the juncture of its two arms, which shaft 84 is secured to a support plate 83 in turn secured to the side plates 34. One arm of the bell crank lever 82 is provided with a connecting pin secured to its free end thereof and extending transversely of the lever and through the 81b end of the L-shaped slot 81, thereby connecting that arm of the bell crank lever to the connecting lever 80 secured by one end to the connecting lever 80 intermediate its ends thereof with a spring 86 which is connected by its other end to the support plate 83. The other arm of the bell crank lever 82 is formed with a fork 87 that captures between the fork arms a lug 89 of a drive bar 88. A pair of spool holders 90 are mounted for rocking movement on pins 91' which pins are secured to the side plates 34 and 114. The drive bar 88 is mounted for endwise slidable movement and is connected at either of its ends to the spool holders 90 as seen more clearly in FIG. 6, the drive bar 88 is formed with two elongated spaced guide slots 92 each of which receive one of the guide pins 91 each one of which is secured to a respective one of the spool holders 90. The drive bar 88 has formed on either of its ends a fork 94. Mounted on one of the spool holders 90 is a spool shaft 95 and on the other spool holder 90 a spool shaft 95a, a ratchet wheel 98 being rotatably mounted on the spool shaft 95 while a ratchet wheel 98a is rotatably mounted on the spool shaft 95a. As seen more clearly in FIG. 5, each of the ratchet wheels 98 and 98a are sandwiched between a spring 96 and a spring washer 97. Mounted for rocking movement on the spool shaft 95 is a support piece 99, that is provided with a center shaft 100 on which is mounted for rocking movement a feed pawl 101. Mounted about the center shaft 100 is a coil spring 102 which is sandwiched between the feed pawl 101 and the support piece 99 and is arranged to provide sufficient elasticity to permit the engagement of the feed pawl 101 with the ratchet wheel 98. The upper (FIG. 5) end section of the center shaft 100 is captured between the legs of the fork 94 of the drive bar 88. A detent pawl 103 is mounted for pivotal movement on a pin 104 which is mounted on each of the spool holders 90. To bias the detent pawl 103 into engagement with the ratchet wheel 98 there is provided a spring 105. The detent pawl is formed with a slide surface 106 and the feed pawl 101 has mounted at its non-ratchet wheel engaging end a roller 107 which when it is brought into engagement with the slide surface 106 prevents the pawl 101 from engaging the ratchet wheel 98. A spool 111 is biased by a spool detent spring 112 (FIG. 5) so that the spool will be driven by the ratchet wheel 98. A length of ribbon 109 is wound about the spool 111 and led through a ribbon guide 108 to the matching ribbon guide on the right hand side (FIG. 6) and through the right side ribbon guide to the right side spool. It is noted that although, in the main, only the apparatus on the left side of the FIG. 6 has been described, the apparatus on the right side is substantially the same and the reference numerals, i. e., 94a, 95a, 98a, 100a, 101a, 103a, 104a, 105a, 106a, 107a, and 1080, are comparable to the corresponding numerals without the letter designation which describe the mechanism shown on the left side of FIG. 6.

Turning now to a description of the operation of the ribbon drive apparatus set forth above, as the cam shaft 1 is driven by the motor (not shown) the cam 72 is rotated in a counterclockwise direction as shown by the appropriate arrow in FIG. 5 thereby driving the roller 73 in the same direction and into engagement with the arm 76 of the fork 74 to pivot the fork clockwise around the shaft 75. The clockwise movement of the fork 74 serves to move the connecting lever to the right, as seen in F IG. 6, through the pin 79, in turn driving the connecting pin to the right also. The movement of the pin 85 serves to rock the bell crank lever 82 counterclockwise (FIG. 6), in turn urging the lug 89 of the drive bar 88 counterclockwise through the forked end section 87 of the bell crank lever 82, thereby moving the drive lever 88 to the left. As the cam 72 continues to rotate, the roller 73 proceeds past the arm 76 of the fork 74 and is brought into engagement with the arm 77 of the fork 74 to rock the fork 74 in the opposite or counterclockwise direction as seen in FIG. 5, thereby to reverse the directions of the elements noted immediately above including the drive lever 88 which is now driven to the right (FIG. 6).

Thus, as described above, the drive bar 88 is driven in endwise reciprocation from one side to the other as seen in FIG. 6. In the condition of the elements as seen in FIG. 6, the connecting pin 85 is positioned at the stability point end 81a of the L-shaped slot 81 formed in the connecting lever and the ratchet 98a and pawl 101a are in engagement one with the other. Thus, the endwise reciprocation of the drive bar 88 serves to move the center shaft a from right to left as seen in FIG. 6 through the fork 94a of the drive bar 88 which fork captures the center shaft 100a between its arms as seen in FIG. 6. As the center shaft 100a is moved to the left (FIG. 6), the pawl 101a which is connected to the center shaft 100a is driven to turn the ratchet 98a clockwise as indicated by the appropriate arrows in FIG. 6. As the ratchet 98a is turned, the associated spool is also rotated in the same direction to pull or take up the ribbon 109 from left to right as seen in FIG. 6. The ratchet 98a meanwhile is prevented from tuming in the opposite direction by the detent pawl a as the feed pawl 101a is-moved back to its original position. Thus, as the drive bar 88 is reciprocated the ribbon 109 is pulled intermittently to the right and wound upon the right spool as it is unwound from the left spool. When the right ratchet 101a is in its operative position the left feed pawl 101 is restrained from its operative position because the left feed pawl 101 has been removed from its operative position by a pawl trip pin which, when actuated, serves to move the pawl 101 out of engagement with the ratchet wheel 98. In addition, when the pawl trip pin 110 is actuated and pivots the pawl 101 clockwise (FIG. 6) out of engagement with the ratchet wheel 98, the other end of the pawl carrying the roller 107 moves in a clockwise direction and slides the roller 107 along the surface 106 of the detent pawl 103, thereby to pivot the detent pawl 103 out of engagement with the ratchet wheel 98. Thus, the reciprocation of the drive bar 88 will have no effect on the left spool because the ratchet wheel 98 cannot be rotated because the pawls 101 and 105 have been removed from engagement with the ratchet wheel 98.

A description of the manner in which the spool driving mechanism is operated to switch the drive from the right spool to the left spool will now be presented. When the ribbon that has been wound upon the left spool is completely unwound therefrom and onto the right spool, the right spool stops rotating because the ends of the ribbon 109 are secured to their respective spools and the pawl 101a can no longer turn the ratchet wheel 98a clockwise because of the resistance of the ribbon 109. Since the cam 72 continues to rotate and the fork 74 continues to drive the connecting lever 80 through the connecting pin 79, the connecting pin 85 will be moved along the substantially L- shaped slot from the stability point end 81a to the stability point end 81b of the slot because of the resistance to counterclockwise movement of the connecting lever 80 by the mechanical train from the bell crank lever 82 to the ratchet wheel 98a. Thereafter, as the bell crank lever 82 is rocked in a clockwise direction (FIG. 6) by the connecting lever '80, the drive bar 88 is moved to the right but, as can be seen from FIG. 7, since the connecting pin 85 is now at the other end (81b) of the slot 81, the drive bar 88 now reciprocates through a range that is advanced to the right (FIG. 7) relatively to the range through which it is reciprocated when the connecting pin 85 was at the 81a end of the slot 81, as seen in FIG. 6. The difference in the ranges as shown in FIG. 6 and FIG. 7 is illustrated by the dash line representation of the bell crank lever 82 and the solid line representation thereof in those two figures in addition to the dashed line and solid line representations of the fork 94a in FIG. 6 and the fork 94 in FIG. 7. As can be seen in FIG. 7, when the fork 94 is shifted to the right most range, the pawl 101 is brought into engagement with the ratchet wheel 98 and the pawl trip pin is moved so that the roller 107 is moved relatively to the surface 106 of the detent pawl 105 thereby allowing the detent pawl 105 to engage with the ratchet wheel 98. Meanwhile, the meshing ends of the pawls 101a and 103a are moved out of engagement with the ratchet wheel 98a by the pawl trip pin 110a just as the pawl 1 had moved the pawls 101 and 103 out of its engagement with the ratchet wheel 98 when the ribbon 109 was being wound upon the right spool as described above. As the drive bar 88 is now reciprocated, the ribbon will be pulled or unwound from the right pawl onto the left pawl in the same manner as the ribbon had been wound on the right pawl as described above. The drive pawl 101 functions to drive the ratchet wheel 98 and the detent pawl 105 prevents the reverse rotation of the ratchet wheel 98 in the same manner as the pawls 101a and 103a cooperate to drive the ratchet wheel 98a in one direction.

There will now be described mechanism for shifting a two color ribbon commonly utilized in calculating machines of the kind to which the present invention is directed. Thus, reference will now be made to a two color ribbon 109 having a band 109a and 10912 (FIG. 5) each of a different color, for example, black and red which is most commonly utilized. The apparatus for selectively shifting the ribbon 109 to present either of the bands 109a or 10% for printing includes a spool holder release mechanism for maintaining the ribbon in a shiftable position and a spool holder rocking drive mechanism for shifting the ribbon. Turning first to a description of the spool holder release mechanism and referring in particular to FIG. 8, there is shown a nonadd key 128 and a total key 132 which extend above the keyboard 33. It has been found desirable to print the values, for example, of the total key and the nonadd keys in one color and the other values in a different color, the mechanism described below being designed to accomplish that end. Thus a release lever 113 of the spool holder 90 is mounted for rocking movement on a pin 115 secured to a side plate 114, the release lever 113 being formed with three arms 116, 117 and 118. On the free end of the arm 116, there is mounted a pin 119 which is received by and protrudes through a slot 120 formed in the side plate 114, the pin 119 being connected to one end of a link 121. On the other end section of the link 121, there is mounted a pin to which is pivotally connected the free end section of an elongated lever 122 pivoted at one end section upon a shaft 123 secured to the side plate 114. The free end section of the elongated lever 122 is formed with a hook 124 that is engageable with-the spool holder 90, as seen in FIG. 8. The release lever 113 is urged in a clockwise (FIG. 8) direction by a coil spring 126 which has one end connected to a pin intermediate the ends of the arm 116 of the release lever 113 and another end connected to a fixed pin. The clockwise movement of the lever 113 and its arm 116 moves the link 121 to the right (FIG. 8) thereby to pivot the elongated lever 122 in a clockwise direction and bring the hook 124 into engagement with the spool holder 90. On the free end of the arm 117 of the release lever 113 there is mounted a pin 117a. The non-add key 128 is supported by a bar which includes an elongated drive bar 127 that is mounted for endwise movement and includes a lug 129 that extends outwardly away from the bar 127 and is aligned with the pin 117a so that as the non-add key 128 is depressed moving the bar 127 downwardly (FIG. 8) the lug 129 is brought into engagement with the pin 1 17a. The remaining arm, 1 18 of the release lever 113, has mounted on its free end a roller 130. The total key 132 is supported by a bar that includes a drive bar 131 mounted for endwise movement and including an elongated slot intermediate its ends thereof. The lower (FIG. 8) or free end of the drive bar 131 is formed with an elongated slot 136 that receives a pin 135 in sliding engagement therewith, the pin 135 being supported on one end section of a rock lever 133. The other end of the rock lever 133 has formed thereon an ear 137 engageable with a lug 140 of an elongated connecting plate 138, the lever 133 being mounted for rocking movement on a rock shaft 134 so that the ear 137 may be brought into or out of engagement with the lug 140. The elongated connecting plate 138 is biased by a spring 139 which is connected by one end to a lug on the plate 138 and by its other end to a fixed pin, to the right as indicated by the appropriate arrow in FIG. 8. The elongated connecting plate 138 is also formed with a lug 141 which is adapted to align with the roller 130 mounted on the free end of the arm 118 of the release lever 113 so that when the elongated connecting plate 138 is moved to the right (FIG. 8) the lug 141 will be brought into engagement with the roller 130 thereby to rock the release lever 113 in a counterclockwise direction.

Turning now to the operationof the spool holder release mechanism, when the operator depresses the non-add key 128 the elongated drive bar 127 is driven downwardly (FIG. 8) thereby to bring the lug 129 into engagement with the pin 117a to rotate the release lever 113 in a counterclockwise direction (FIG. 8) against the bias exerted by the spring 126. When the total key 138 is depressed by the operator the drive bar 131 is moved downwardly (FIG. 8) thereby to rock the lever 133 clockwise through the interrnediacy of the pin 135 in the slot 136 to release the ear 137 from engagement with the lug 140 so that the spring 139 may urge the connecting plate 138 to the right as seen in FIG. 8. When the connecting plate 138 is moved to the right the lug 141 engages and moves the rollerl30 in the same direction thereby rocking the release lever 113 in a counterclockwise direction about the pin 115. Thus, when either of the keys 128 or 132 are depressed, the release lever 113 is rocked in a counterclockwise (FIG. 8) direction about the pin 115 against the bias exerted by the spring 126. The counterclockwise movement of the release lever 113 serves to move the hook 124 out of engagement with the spool holder 90 through the interrnediacy of the pin 1 l9, link 121 and pin 125. By releasing the hook 124 from engagement with the spool holder 90, the latter is in condition for shifting of the ribbon 109 from one to the other of the differently colored bands 109a and 10%.

Reference may be had in particular to FIG. 5 for the following description of the rocking drive mechanism for the spool holders. Thus, the cam surface of the cam 72 is engaged by a cam follower roller 145 mounted on one end of a rock lever 143 which in turn is mounted intermediate its ends for rocking movement about a shaft 144 secured to the side plate 34. The lever 143 is urged in a counterclockwise (FIG. 5) direction by a coil spring 146 which is connected by one end to .the rock lever 143 between the shaft 144 and the roller end of the lever 143 and by its other end to a fixed pin, thereby biasing the roller 145 into engagement with the cam surface of the cam 72. The cam surface of the cam 72 is substantially circular except for one section thereof which extends radially thereof and forms a land or raised shoulder 142. The other end section of the lever 143 is bifurcated to form a fork 147 which receives a pin 148, secured to the spool holder 90 between the arms of the fork 147. The locking movement of each spool holder will now be described. As the motor (not shown) drives the cam or motor shaft 1 and the shaft secured cam 72 in a counterclockwise direction as shown by the appropriate arrow in FIG. 1, the roller 145, biased into sliding engagement with the cam surface of the cam 72, slides down off the land 142 (assuming that the roller was in the position as shown in FIG. 5) and down onto the circular portion of the cam surface. As this occurs, the rock lever 143 is rocked in a counterclockwise direction as indicated by the appropriate arrow in FIG. 5 by the force exerted by the spring 146. If the spool holder 90 has not been released from engagement with the hook 124, at the time that the rock lever 143- is urged in a counterclockwise direction by the spring 146, as described above, the lever 143 is unable to rock in the counterclockwise direction. However, if the spool holder 90 is in its released condition, the lever 143 will be rocked in the counterclockwise direction thereby urging the fork 147 in the same counterclockwise direction thereby to move the spool holder 90 clockwise (FIG. 5) around the pin 91', through the interrnediacy of the pin 148 which is connected to the spool holder 90. If, in the above described series of movements, the color band 109a of the ribbon 109 is in its printing position, i.e., aligned between the platen 20 and the type disc, as shown in FIG. 5, the rocking movement of the spool holder in the clockwise direction around the pin 91' serves to bring the other color band 10% into the described printing position so that the printing will be made with the color band 10% instead of the color band 109a.

The only time that the spool holder 90 is free for rocking movement in a clockwise direction around the pin 91' is when the hook 124 has been disengaged from the spool holder 90, and the only time that the disengagement is effected is when either of the keys 128 or 132 is depressed. Thus, the only times that printing is effected utilizing the color band 10% of the ribbon 109 are when either of the keys 128 or 132 is depressed. After the cam 72 has made one complete revolution the land 142 is brought back into engagement with the roller thereby rocking the lever 143 in the clockwise (FIG. 5) direction, thereby to rock the spool holder 90 counterclockwise around the pin 91' back to its original position. From the foregoing it can be understood that the depression of the keys 128 and 132 will always produce a printing of the characters having a non-add or total value in one color. When any of the other keys of the machine such as the total key is depressed, the other color of the two colors produced by the ribbon 109 will be reflected in the printed characters produced thereby.

Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of our invention which is forpurposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.

What we claim and desire to secure by letters patent is: e

1. In a calculating machine having a platen; a plurality of type units; means for selectively moving said platen into engagement with the plurality of type units for performing a printing operation comprising a movable platen drive arm, means including a driving connection between said platen and said platen drive arm for effecting movement of said platen in response to driving movement of said platen drive arm, means for effecting driving movement of said platen drive arm, and wherein said driving connection comprises a member connected to said platen and in operative engagement with said platen drive arm; and connection means for preventing the printing of erroneous values including a manually actuatable correction element, and means for interrupting the driving connection between said platen and said platen drive arm to effectively prevent engagement of said platen with the plurality of type units upon manual actuation of the correction element, said lastmentioned means including an indent in said platen drive arm for receiving therein said member when said correction element is manually actuated and said platen drive arm is driven by said means for driving said platen drive arm.

2. In a calculating machine as set forth in claim 1 wherein said means for interrupting the driving connection between said platen and said platen drive arm includes a release arm operatively connected to said correction element and movable into engagement with said platen drive arm when said correction element is actuated to move said platen drive arm and bring said indent into alignment with said member.

3. In a calculating machine as set forth in claim 2 wherein said member is a pin and wherein said platen drive arm includes a shoulder engaged by said pin, said shoulder being driven by said means for driving said platen drive arm into engagement with said pin, the movement of said platen drive arm serving to move said pin to move said platen into engagement with said type units, said shoulder being spaced from said indent in the direction of movement of said platen drive arm against said pin so that when said pin is moved off of said shoulder and said indent is aligned with said pin further movement of the platen drive arm will not move said pin which is then received by the indent.

4. In a calculating machine as set forth in claim 1 including a non-add lever, means for actuating the nonadd lever, the actuation thereof placing an accumulator in a neutral position.

5. In a calculating machine as set forth in claim 4 wherein said means for actuating said non-add lever includes release means selectively engageable with said non-add lever for locking said non-add lever against actuation thereof and for releasing said non-add lever for actuation thereof when said release means is actuated, said release means including a release lever which when actuated actuates said non-add lever and an arm operatively connected to said manually actuatable correction element for actuating said release lever upon actuation of said manually actuable correction element.

6. In a calculating machine as set forth in claim 1 including a pair of ribbon spools and means for winding ribbon into a first one of said spools from the second one of said spools said last named means including an endwise reciprocatory drive bar, means for driving said drive bar in endwise reciprocation and means for shifting the ribbon winding from the first ribbon spool to the second ribbon spool.

7. In a calculating machine as set forth in claim 6 including means for connecting said drive bar to said first spool to drive said first spool and means for connecting said drive bar to said second spool to drive said second spool when said shifting means is actuated.

' 8. ln a calculating machine as set forth in claim 1 including means for shifting ribbon having a first and a second band from a first position wherein the first band is utilized for printing to a second position wherein the second band is utilized for printing, in response to the actuation of certain predetermined calculating machine control members.

9. In a calculating machine as set forth in claim 8 wherein said shifting means includes'a hook lever having a locking position for retaining the ribbon in its first position and a release position for permitting movement of said ribbon to its second position and a release means for moving said hook lever to its release position upon actuation of certain predetermined calculating machine control members.

10. In a calculating machine having a platen; a plurality of type units; means for selectively moving said platen into engagement with the plurality of type units for performing a printing operation comprising a movable platen drive arm, means including a driving connection between said platen and said platen drive arm for effecting movement of said platen in response to driving movement of said platen drive arm, and means for effecting driving movement of said platen drive arm; connection means for preventing the printing of erroneous values including a manually actuatable correction element, and means for interrupting the driving connection between said platen and said platen drive arm to effectively prevent engagement of said platen with the plurality of type units upon manual actuation of the correction element; a non-add lever; means for actuating said non-add lever; and means for holding said correction element and said non-add lever actuated for a predetermined period.

11. In a calculating machine as set forth in claim 10 including a movable connecting member operatively connected to said correction element and said non-add lever and means for moving said movable connecting member from a first to a second position when said correction element is actuated and said holding means including means for holding said movable connecting member in the second position for the predetermined period.

12. In a calculating machine as set forth in claim 11 including a driven shaft and wherein said means for holding said movable connecting member includes a detent lever operatively connected to said driven shaft and said movable connecting member and means for actuating said detent lever for releasing the movable connecting member from the second position after said driven shaft has turned through a predetermined angle.

13. In a calculating machine having a platen; a plurality of type units; means for selectively moving said platen into engagement with the plurality of type units for performing a printing operation comprising a movable platen drive arm, means including a driving connection between said platen and said platen drive arm for effecting movement of said platen in response to driving movement of said platen drive arm, means for effecting driving movement of said platen drive arm, and wherein said driving connection between said platen and said platen drive arm comprises a projecting member connected to said platen engageable with a surface portion of said platen drive arm; and connection means for preventing the printing of erroneous values including a manually actuatable correction element, and means for interrupting the driving connection between said platen and said platen drive arm to effectively prevent engagement of said platen with the plurality of type units upon manual actuation of the correction element, said means for interrupting the driving connection between said platen and said platen drive arm comprising means defining a slot in said platen drive arm, means mounting said platen drive arm for pivotal movement to a first position wherein said projecting member engages with said surface portion of said platen drive arm to effect movement of said platen in response to driving movement of said platen drive arm and to a second position in response to manual actuation of said correction element wherein said projecting member is received within said slot in said platen drive arm during driving movement of said platen drive arm while said platen remains stationary, and means continually biasing said platen drive arm in said first position.

14. In a calculating machine as set forth in claim 13; a pivotally mounted link having means thereon engageablewith said platen drive arm to effect pivotal movement thereof to said second position in response to pivotal movement of said link, and a mechanical linkage system interconnecting said correction element with said link operative to effect pivotal movement of said link in response to manual actuation of said correction element.

15. In a calculating machine as set forth in claim 13; wherein said means for effecting driving movement of said platen drive arm comprises a pivotally mounted platen drive lever connected to said platen drive arm, and camming means for'pivoting said platen drive lever to accordingly effect driving movement of said platen drive arm, 

1. In a calculating machine having a platen; a plurality of type units; means for selectively moving said platen into engagement with the plurality of type units for performing a printing operation comprising a movable platen drive arm, means including a driving connection between said platen and said platen drive arm for effecting movement of said platen in response to driving movement of said platen drive arm, means for effecting driving movement of said platen drive arm, and wherein said driving connection comprises a member connected to said platen and in operative engagement with said platen drive arm; and connection means for preventing the printing of erroneous values including a manually actuatable correction element, and means for interrupting the driving connection between said platen and said platen drive arm to effectively prevent engagement of said platen with the plurality of type units upon manual actuation of the correction element, said last-mentioned means including an indent in said platen drive arm for receiving therein said member when said correction element is manually actuated and said platen drive arm is driven by said means for driving said platen drive arm.
 2. In a calculating machine as set forth in claim 1 wherein said means for interrupting the driving connection between said platen and said platen drive arm includes a release arm opeRatively connected to said correction element and movable into engagement with said platen drive arm when said correction element is actuated to move said platen drive arm and bring said indent into alignment with said member.
 3. In a calculating machine as set forth in claim 2 wherein said member is a pin and wherein said platen drive arm includes a shoulder engaged by said pin, said shoulder being driven by said means for driving said platen drive arm into engagement with said pin, the movement of said platen drive arm serving to move said pin to move said platen into engagement with said type units, said shoulder being spaced from said indent in the direction of movement of said platen drive arm against said pin so that when said pin is moved off of said shoulder and said indent is aligned with said pin further movement of the platen drive arm will not move said pin which is then received by the indent.
 4. In a calculating machine as set forth in claim 1 including a non-add lever, means for actuating the non-add lever, the actuation thereof placing an accumulator in a neutral position.
 5. In a calculating machine as set forth in claim 4 wherein said means for actuating said non-add lever includes release means selectively engageable with said non-add lever for locking said non-add lever against actuation thereof and for releasing said non-add lever for actuation thereof when said release means is actuated, said release means including a release lever which when actuated actuates said non-add lever and an arm operatively connected to said manually actuatable correction element for actuating said release lever upon actuation of said manually actuable correction element.
 6. In a calculating machine as set forth in claim 1 including a pair of ribbon spools and means for winding ribbon into a first one of said spools from the second one of said spools said last named means including an endwise reciprocatory drive bar, means for driving said drive bar in endwise reciprocation and means for shifting the ribbon winding from the first ribbon spool to the second ribbon spool.
 7. In a calculating machine as set forth in claim 6 including means for connecting said drive bar to said first spool to drive said first spool and means for connecting said drive bar to said second spool to drive said second spool when said shifting means is actuated.
 8. In a calculating machine as set forth in claim 1 including means for shifting ribbon having a first and a second band from a first position wherein the first band is utilized for printing to a second position wherein the second band is utilized for printing, in response to the actuation of certain predetermined calculating machine control members.
 9. In a calculating machine as set forth in claim 8 wherein said shifting means includes a hook lever having a locking position for retaining the ribbon in its first position and a release position for permitting movement of said ribbon to its second position and a release means for moving said hook lever to its release position upon actuation of certain predetermined calculating machine control members.
 10. In a calculating machine having a platen; a plurality of type units; means for selectively moving said platen into engagement with the plurality of type units for performing a printing operation comprising a movable platen drive arm, means including a driving connection between said platen and said platen drive arm for effecting movement of said platen in response to driving movement of said platen drive arm, and means for effecting driving movement of said platen drive arm; connection means for preventing the printing of erroneous values including a manually actuatable correction element, and means for interrupting the driving connection between said platen and said platen drive arm to effectively prevent engagement of said platen with the plurality of type units upon manual actuation of the correction element; a non-add lever; means for actuating said non-add lever; and means For holding said correction element and said non-add lever actuated for a predetermined period.
 11. In a calculating machine as set forth in claim 10 including a movable connecting member operatively connected to said correction element and said non-add lever and means for moving said movable connecting member from a first to a second position when said correction element is actuated and said holding means including means for holding said movable connecting member in the second position for the predetermined period.
 12. In a calculating machine as set forth in claim 11 including a driven shaft and wherein said means for holding said movable connecting member includes a detent lever operatively connected to said driven shaft and said movable connecting member and means for actuating said detent lever for releasing the movable connecting member from the second position after said driven shaft has turned through a predetermined angle.
 13. In a calculating machine having a platen; a plurality of type units; means for selectively moving said platen into engagement with the plurality of type units for performing a printing operation comprising a movable platen drive arm, means including a driving connection between said platen and said platen drive arm for effecting movement of said platen in response to driving movement of said platen drive arm, means for effecting driving movement of said platen drive arm, and wherein said driving connection between said platen and said platen drive arm comprises a projecting member connected to said platen engageable with a surface portion of said platen drive arm; and connection means for preventing the printing of erroneous values including a manually actuatable correction element, and means for interrupting the driving connection between said platen and said platen drive arm to effectively prevent engagement of said platen with the plurality of type units upon manual actuation of the correction element, said means for interrupting the driving connection between said platen and said platen drive arm comprising means defining a slot in said platen drive arm, means mounting said platen drive arm for pivotal movement to a first position wherein said projecting member engages with said surface portion of said platen drive arm to effect movement of said platen in response to driving movement of said platen drive arm and to a second position in response to manual actuation of said correction element wherein said projecting member is received within said slot in said platen drive arm during driving movement of said platen drive arm while said platen remains stationary, and means continually biasing said platen drive arm in said first position.
 14. In a calculating machine as set forth in claim 13; a pivotally mounted link having means thereon engageable with said platen drive arm to effect pivotal movement thereof to said second position in response to pivotal movement of said link, and a mechanical linkage system interconnecting said correction element with said link operative to effect pivotal movement of said link in response to manual actuation of said correction element.
 15. In a calculating machine as set forth in claim 13; wherein said means for effecting driving movement of said platen drive arm comprises a pivotally mounted platen drive lever connected to said platen drive arm, and camming means for pivoting said platen drive lever to accordingly effect driving movement of said platen drive arm. 